JP2015510613A - Display with non-woven diffuser - Google Patents

Abstract

The present disclosure describes a display system that includes a liquid crystal display panel and a light source that emits light having the ability to emit light. The nonwoven diffuser element is disposed between the light source and the liquid crystal display panel. The polymeric nonwoven diffuser is non-oriented and has a fiber diameter of less than 50 micrometers, a fiber aspect ratio of length / diameter greater than 5, and a basis weight in the range of 10-80 grams / m 2. .

Description

  The present disclosure particularly relates to displays with nonwoven diffusers.

  Liquid crystal displays (LCDs) are optical displays used in devices such as laptop computers, handheld calculators, digital watches, and televisions. Some LCDs include a light source with a light guide located on the side of the display and positioned to guide light from the light source to the back of the LCD panel. Other LCDs (eg, some LCD monitors and LCD televisions (LCD-TVs)) are directly illuminated using a number of light sources positioned behind the LCD panel. This arrangement means that for larger displays, the light output requirement to achieve a certain level of display brightness increases in proportion to the square of the display dimensions, but the light source along the side of the display Available scaffolds for positioning are becoming increasingly common as they only increase linearly with display size. In addition, some LCD applications, such as LCD-TV, require the display to be bright enough to be viewed from a greater distance than other applications, and viewing angle requirements for LCD-TV are LCD monitors and It is usually different from that for handheld devices.

  Some LCD monitors and LCD-TVs are typically illuminated from behind by many cold cathode fluorescent lamps (CCFLs). These light sources are linear and stretched across the full width of the display so that the back of the display is illuminated by a series of bright streaks separated by darker areas. Such an illumination profile is undesirable, so a diffuser plate is used to smooth the illumination profile at the back of the LCD device.

Many LCD-TV diffuser plates employ a polymeric matrix of polymethyl methacrylate (PMMA) with various dispersed phases including glass, polystyrene beads, and CaCO ₃ particles. These plates often deform or warp after being exposed to the high temperature of the lamp. In addition, some diffusion plates have diffusion characteristics that vary spatially across their width in an attempt to make the illumination profile on the back of the LCD panel more uniform. Such non-uniform diffusers are sometimes referred to as printed pattern diffusers. They are expensive to manufacture and the diffusion pattern needs to be matched with the illumination source during assembly, thus increasing manufacturing costs. In addition, the diffusion plate requires a custom extrusion that is synthesized to evenly distribute the diffusing particles through the polymer matrix, which further increases cost.

  The present disclosure relates to a display with a nonwoven diffuser, among other aspects.

In many embodiments, a display system is described. The display system includes a liquid crystal display panel and a light source that emits light having the ability to emit light. The nonwoven diffuser element is disposed between the light source and the liquid crystal display panel. The polymeric nonwoven diffuser is non-oriented, having a fiber diameter of less than 50 micrometers, a fiber aspect ratio of length / diameter greater than 5, and a basis weight in the range of 10-80 grams / m ^2. Have.

  In many embodiments, the display system includes a liquid crystal display panel and a light source that emits light capable of emitting light. The polymer nonwoven diffuser element is disposed between the light source and the liquid crystal display panel. The polymeric nonwoven diffuser is non-oriented, has a visible light transmission of 50% or more, and an effective transmission of 0.9 or more.

A more complete understanding of the present disclosure can be obtained by considering the following detailed description of various embodiments of the disclosure in conjunction with the accompanying drawings.
1 is a schematic diagram of an illustrative display system. FIG. 2 is a schematic side view of an illustrative diffuser. FIG. 1 is a schematic diagram of an illustrative system for measuring effective transmission. FIG.

  The schematic drawings shown here are not necessarily to scale. Like numbers used in the figures refer to like components, steps, and the like. However, it will be understood that the use of numbers to refer to components in a given figure is not intended to limit components in another figure that are numbered the same. In addition, the use of different numbers to refer to components is not intended to mean that different numbered components cannot be the same or similar.

  In the following Detailed Description, reference is made to the accompanying drawings that form a part hereof, which are shown by way of illustration of several specific embodiments of the devices, systems, and methods. . It is to be understood that other embodiments are contemplated and may be made without departing from the spirit and scope of the present disclosure. Accordingly, the following detailed description should not be taken in a limiting sense.

  All scientific and technical terms used herein have meanings commonly used in the art unless otherwise indicated. The definitions provided herein are intended to facilitate understanding of certain terms frequently used herein and are not meant to limit the scope of the present disclosure.

  As used herein and in the appended claims, the singular forms “a”, “an”, and “the” include plural referents unless the content clearly dictates otherwise. Including the embodiment.

  As used herein and in the appended claims, the word “or” is generally used in its sense including “and / or” unless the content clearly dictates otherwise. It is done.

  As used herein, “have”, “having”, “include”, “including”, “comprise”, “comprising”, etc. Is used in an unrestricted sense and generally means “including but not limited to”. It will be understood that the terms “consisting of” and “consisting essentially of” are encompassed by terms such as “comprising”.

  Any direction as used herein, such as “top”, “bottom”, “left”, “right”, “top”, “bottom”, “upward”, “downward”, and other directions, As well as orientation is described herein for clarity with reference to the figures, and does not limit the actual device or system or use of the device or system. Many of the devices, articles or systems described herein can be used in many directions and orientations.

  The present disclosure describes, among other things, a display with a non-woven diffuser. In particular, the present disclosure relates to a display with a nonwoven diffuser that has high transparency, high haze, low transparency, and provides uniform light emission. Nonwoven diffusers have the brightness enhancement capability and image hiding of light sources such as, for example, LCD system backlight CCFLs and LEDs. While the present disclosure is not so limited, through consideration of the examples provided below, applications of various aspects of the disclosure will be obtained.

  FIG. 1 is a schematic diagram of an exemplary display system 100. The display system 100 includes a liquid crystal display panel 120 and a light source 110 capable of emitting light. On the other hand, although an edge-lit display system 100 is illustrated, the system may be a direct-light display system or a back-lit display system, or a combination of a direct-light display or a back-lit display. It is understood that you can.

  The illustrated display system 100 includes a light source 110 that emits light into a light guide plate 112, which emits light through a light emitting surface 114. The nonwoven diffuser element 130 is disposed between the light emitting surface 114 and the liquid crystal display panel 120. Although an edge-lit display system 100 is illustrated, it is understood that the system can be a direct-light display system or a back-lit display system.

  FIG. 2 is a schematic side view of an exemplary diffuser 130. The vertical light L1 passes through the nonwoven diffuser element 130 relatively easily. The high angle light L2 is scattered or diffused by the fibers of the nonwoven diffuser element 130, and a portion of this light L2 is emitted at a relatively normal angle. Thus, the non-woven diffuser element 130 can improve the on-axis brightness of light emitted through the non-woven diffuser element 130.

  Nonwoven diffuser element 130 can be formed by any useful process. Nonwoven diffuser element 130 can be formed, for example, via a wet laid process, a card process, a meltblown process, spunbond, dry laid, spunbond-meltblown-spunbond. The nonwoven diffuser element 130 can be embossed or calendered as desired. The nonwoven diffuser element 130 can be described as being generally non-oriented. In some embodiments, the manufacturing process can produce a slight orientation, yet this is generally considered non-oriented.

  The nonwoven diffuser element 130 can be formed of multiple layers of nonwoven elements. The nonwoven diffuser element 130 can be suspended in the display system by being attached at two or more edges of the nonwoven diffuser element 130. In some embodiments, the non-woven diffuser element 130 is attached to a support substrate or optical element in the display system.

  When the nonwoven diffuser 130 is placed on an optical cavity, such as a backlight, it can act as a brightness enhancement film. Light rays that are incident from a near-normal angle normal to the optical cavity surface and the non-woven diffuser 130 travel through the non-woven fiber structure with little diffusion or scattering. Light rays from higher tilt angles (high angles) hit the nonwoven fibers of the structure and are likely to be diffused and / or scattered. When the polymer nonwoven diffuser is viewed at a vertical angle, the polymer nonwoven diffuser appears to be transparent, and when viewed at a high angle, the polymer nonwoven diffuser is opaque and / or It looks cloudy. Therefore, due to the above phenomenon, the light beam appears to collimate at a vertical angle.

In many embodiments, the polymeric nonwoven diffuser 130 has a fiber diameter of less than 50 micrometers, a fiber aspect ratio greater than 5 length / diameter, and a basis weight in the range of 10-80 grams / m ^2. Have. In some embodiments, the polymeric nonwoven diffuser 130 has a fiber diameter of less than 25 micrometers, or in the range of 1-25 micrometers, or in the range of 10-25 micrometers. In some embodiments, the polymeric nonwoven diffuser 130 has a basis weight in the range of 20-70 grams / m ² . In some embodiments, the polymeric nonwoven diffuser element 130 has a density of 0.1 g / cm ³ or higher, or 0.15 g / cm ³ or higher, or 0.2 g / cm ³ or higher.

  The polymeric nonwoven diffuser 130 is non-oriented and may exhibit high haze, high transparency, low transparency and provides uniform light emission. In many embodiments, the polymeric nonwoven diffuser element 130 has a visible light transmission of 50% or more, or 60% or more, or 65% or more, or 70% or more. The polymeric nonwoven diffuser element 130 has an effective transmittance of 0.9 or greater, or 1.0 or greater. The polymeric nonwoven diffuser element 130 has a haze of 80% or more, or 85% or more, or 90% or more, or 95% or more. The polymeric nonwoven diffuser element 130 has a transparency of 70% or less, or 60% or less, or 50% or less.

  Nonwoven diffuser 130 can be formed of any useful polymeric material. In many embodiments, the polymeric nonwoven diffuser 130 can be formed of polyethylene, polypropylene, and polyethylene terephthalate, or engineering plastics such as, for example, polybutylene terephthalate, and polyphenylene sulfide. In some embodiments, the nonwoven diffuser 130 can be formed of glass fibers.

  In some embodiments, the resin material at least partially fills the nonwoven diffuser 130. The resin can be any useful resin material. In some embodiments, the resin is a curable (eg, UV curable) resin material.

  Some of the advantages of the disclosed system and construction are further illustrated by the following examples. The specific materials, amounts and dimensions described in this example, as well as other conditions and details, should not be construed to unduly limit this disclosure.

The display system (see FIGS. 1 and 100) was constructed using E2041T liquid crystal display (LCD) 120 from LG Corporation (Youngdungpo-gu Seoul, Korea). The display was modified by removing the existing film and replacing it with a bead-only diffuser or non-woven diffuser 130. The gain diffuser is an existing gain diffuser in the LG Corporation display, and the tested non-woven diffuser 130 is Freudenberg Nonwovens 2431 (Weinheim, Germany), Asahi Kasei Corporation A5130 (Tokyo, Japan), Crane & Co. . , Inc. RS 8.5 (Dalton, Massachusetts), Midwest Filtration Company Unified 100 (Cincinnati, Ohio), Fredenber Nonoves 2483 (Weinheim, Germany). For all samples listed herein, the fiber aspect ratio of length / diameter is considered to be greater than 5. The tested samples had the functional and structural qualities shown in FIG. The results of various tests are reported in Table 1 below.

The effective transmission was measured using the effective transmission measurement system described below.
Effective transmission is the ratio of the brightness of a display system with the film mounted in place in the display system relative to the brightness of the display where the film is not in place. Effective transmittance (ET) can be measured using the optical system illustrated in FIG. The optical system 200 includes a hollow Lambertian light box that radiates Lambertian light 215 about the optical axis 250 and emits Lambertian light 215 through the exit surface 212, a linear light absorbing polarizer 220, and a photodetector 230. . The light box 210 is illuminated by a stable broadband light source 260 connected to the inside 280 of the light box via an optical fiber 270. A test sample measuring ET by optics was placed in a location 240 between the light box and the absorbing linear polarizer.

The ET of the nonwoven diffusion film 130 can be measured by placing the nonwoven diffusion film 130 at location 240. The spectrally weighted axial luminance I ₁ (luminance along the optical axis 250) is then measured by the photodetector through a linear absorption polarizer. Next, the nonwoven diffuse film 130 is removed and the spectrally weighted luminance I ₂ is measured without the nonwoven diffuse film 130 placed at location 240. ET is the ratio of I ₁ / I ₂ .

  As used herein, light haze is defined as the ratio of emitted light that deviates more than 4 degrees from the vertical to the total emitted light. The haze values disclosed herein were measured using a Haze-Gard Plus haze meter (available from BYK-Gardiner, Silver Springs, Md) according to the procedure described in ASTM D1003.

As used herein, optical transparency refers to the ratio of 1- (T ₁ −T ₂ ) / (T ₁ + T ₂ ) (absolute value), where T ₁ is from the vertical direction. The emitted light from the vertical direction, shifted by 1.6 degrees to 2 degrees, and T ₂ is the emitted light at 0 degrees to 0.7 degrees from the vertical direction. The transparency values disclosed herein were measured using a BYK-Gardiner Haze-Gard Plus haze meter.

  As used herein, optical transmission (ie, total transmission) is the ratio (expressed as a percentage) of the luminance flux that radiates through a surface relative to the light flux incident on the surface. ) Specifically, this is the number reported by the Haze-Gard Plus system according to the D1003 ASTM standard.

  The LG LCD low voltage differential signal (LVDS) connector was disconnected to produce a white screen when the display was turned on. Finally, brightness measurements were taken using a Radiant Imaging ProMetric camera from Pro-Lite Technology Ltd (Northampton, United Kingdom) with a 50mm lens from Sigma Corporation (Kanagawa, Japan).

  The measurement taken was the average brightness of the display cross-section at the center, measured over 161 mm. The result for each nonwoven was then divided by the brightness measured for the gain diffuser to obtain the relative brightness. Uniformity was judged visually against existing gain diffusers and evaluated on a scale of 1-3. 3 represents the uniformity level of the gain diffuser, 2 represents adequate uniformity, and 1 represents unacceptable uniformity. The results are the average of 4 different observers and are summarized in Table 2 along with the brightness.

  For the edge type system shown in FIG. 1, the tested samples that showed adequate gain and uniformity were Freudenberg 2431, Freudenberg 2483, and Crane RS 8.5. In previous experiments, A5130 showed adequate uniformity and brightness in direct light systems.

Nonwoven Density Example Set The display system was constructed as described above. The non-woven diffuser tested was a 1 meter wide double-duffer card machine from Hergeth-Hollingsworth (Dulmen, Germany) with a card process of 32 feet per minute (9.8 meters) to 40 gsm web batting. Produced and then sent to a high temperature air conveyor belt furnace (IHEI Inc., Franklin, WI) at 32 fpm (975.4 cm / min) at 140 ° C. to stabilize the web. The fibers used in these nonwoven fabrics are Stein Inc. , Albany, NY, a two-denier polyester bicomponent long fiber (Style 131-00251). Subsequently, the web was passed through a 125 ° C. flat calendar roll at various intervals at 5 feet per minute to achieve different densities as described in Table 3 below. .

  Fiber diameter was measured using a Hirox Digital microscope model number KH7700 (Hackensack, New Jersey). Effective transmission, transmission, haze, transparency, brightness, and uniformity were measured using the methods described above.

  The results are the average of 4 different observers and are summarized in Table 4 along with the brightness.

Therefore, sample 4 (0.8 g / cm ³ ) was an appropriate sample with respect to brightness and uniformity.

Example of Resin Filled Nonwoven Fabric A5100 nonwoven sample from Asahi Kasei (Tokyo, Japan) was used as the precursor material. A5100 is a spunbond-meltblown-spunbond 20 gsm nonwoven composite, and the meltblown layer has a fiber diameter in the range of 2-3 micrometers. The sample was then modified by the following procedure.

  A UV curable acrylate adhesive resin (UVX-1962 from Toagosei, Tokyo, Japan) was applied to the PET film using the wire bar coating method (wire bar gauge size is either 5 or 12). For Samples 3, 4, and 5, where the PET film was removed after curing, the PET film had a silicone layer to facilitate removal. For sample 2, an uncoated PET film was used. Sample 1 was not coated with resin and was used as a control.

  The A5100 nonwoven material is pressed against the PET film with a UVX-1962 resin coating. For sample 5, UVX-1962 is again applied to A5100 to embed the nonwoven fibers.

  The sample was then placed in a UV furnace to cure the UVX-1962 resin.

  After curing of the resin, the PET was removed from Samples 3, 4, and 5, leaving only the resin coated nonwoven.

  Sample performance was measured. The results are reported in Table 5 below.

  The effective transmission was measured as described in the examples above.

  The overall transmittance and haze level were measured according to JIS K7361-1: 1997 and JIS K7136: 2000 test standards using an ND-2000 haze meter (available from Nippon Denshoku Industries Co., Ltd., Tokyo, Japan). It was done. The light source used was a standard D65 type.

  Thus, an embodiment of a “display with nonwoven diffuser” is disclosed. Those skilled in the art will appreciate that the optical films and film articles described herein can be implemented in embodiments different from those disclosed. The disclosed embodiments are presented for purposes of illustration and not limitation.

Claims (22)

A display system,
A liquid crystal display panel;
A light source that has the ability to emit light;
A polymeric nonwoven diffuser element optically between the light source and the liquid crystal display panel;
Including
The polymeric nonwoven diffuser is non-oriented, a fiber diameter of less than 50 micrometers, a fiber aspect ratio of length / diameter greater than 5, and a basis weight in the range of 10-80 grams / m ² ; A display system.   The display system according to claim 1, wherein the display system is a direct light display system.   The display system according to claim 1, wherein the display system is an edge light type display system. The display system according to claim 1, wherein the polymer nonwoven diffuser element has a density of 0.15 g / cm ³ or more.   The display system according to claim 1, wherein the polymer nonwoven diffuser element has a visible light transmittance of 50% or more.   The display system according to claim 1, wherein the polymer nonwoven diffuser element has an effective transmittance of 0.9 or more.   The display system according to claim 1, wherein the polymer non-woven diffuser element has a haze of 80% or more.   The display system according to claim 1, wherein the polymer non-woven diffuser element has a transparency of 70% or less.   The display system according to claim 1, wherein the polymer non-woven diffuser element includes a resin filling at least a part of the non-woven diffuser element. A display system,
A liquid crystal display panel;
A light source that has the ability to emit light;
A polymeric nonwoven diffuser element optically between the light source and the liquid crystal display panel;
Including
A display system wherein the polymeric nonwoven diffuser is non-oriented and has a visible light transmission of 50% or more and an effective transmission of 0.9 or more.   The display system of claim 9, wherein the display system is a direct light display system.   The display system according to claim 9, wherein the display system is an edge light type display system. The polymeric nonwoven diffuser element has a 0.15 g / cm ³ or more density, display system as claimed in any one of claims 9 to 11.   13. A display system according to any one of claims 9 to 12, wherein the polymeric nonwoven diffuser element has a fiber diameter of less than 50 micrometers.   14. A display system according to any one of claims 9 to 13, wherein the polymeric nonwoven diffuser element has a fiber aspect ratio of length / diameter greater than 5. The polymeric nonwoven diffuser element has a basis weight in the range of 10 to 80 g / m ^2, a display system according to any one of claims 9-14.   The display system according to any one of claims 9 to 15, wherein the polymer nonwoven diffuser element has a haze of 80% or more.   The display system according to any one of claims 9 to 16, wherein the polymer non-woven diffuser element has a transparency of 70% or less.   18. A display system according to any one of claims 9 to 17, wherein the polymeric nonwoven diffuser element has a visible light transmission of 65% or more.   The display system according to any one of claims 9 to 18, wherein the polymer nonwoven diffuser element has an effective transmittance of 1.0 or more.   20. A display system according to any one of claims 9 to 19, wherein the polymeric nonwoven diffuser element has a haze of 90% or more and a transparency of 70% or more.   The display system according to claim 1, wherein the polymer non-woven diffuser element includes a resin filling at least a part of the non-woven diffuser element.

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